Setting Up Data Link Server on Linux

Before you can use Data Connectors you must have a running instance of the Data Link Server. The Data Link Server is a Java web application, hosted on an embedded Apache Tomcat HTTP server that relays and translates any requests made to your Telerik Platform app to your relational database.

This article explains the installation of a Data Link Server on a Linux machine. In order to install it on a machine running Microsoft Windows, follow the instructions in Setting Up Data Link Server on Windows.

You can run the server application once or install it as a system service for continuous running.

When the server is starting it reads the application.properties configuration file. Always check if it is set up correctly otherwise the server uses default values. You can learn how and when to set some of the more important options in the remaining sections of this article. Keep in mind that configuration updates take effect after restarting the Data Link Server.

Running the server from the command line is not the best solution if you need it always running. A better alternative is to install it as a service, so it is started automatically when the machine boots.
The Data Link Server comes with an installation script that generates an Upstart configuration and starts the service.

To install the service, open a terminal window and go to the bin directory inside the folder where you extracted the Data Link Server package, then run the command below as root. The only required parameter (datalinkuser in the example) is the name of a local user account that will be used to run the service.

For the following instructions, you need to be executing the commands as the root user.

The easiest way to check if the Data Link Server server is running is to access its URL (http://machine-name.domain:port) with the curl command. For example, if you are testing from the machine where the server is installed and it runs on the default port, the URL would be http://localhost:9090. The expected response is HTTP status code 200 and a simple JSON-formatted message:

The security is not complete without configuring the server-to-server authentication between Telerik Platform and your instance of the Data Link Server. The integrated authentication mechanism restricts the access to your Data Link Server, allowing in only a Telerik Platform app authenticated with an appointed key known to both parties. The secret key is automatically generated for each Telerik Platform app.

Alternatively, you can use the RESTful API to download the authentication key.

The file name of your download will be the Telerik Platform App ID followed by the .txt file extension (for example 3YVPn8Al5Vi8Yfe4.txt). The content of the file is a JSON Web Token, the secret key used by Telerik Platform and the Data Link Server to sign and validate requests.

Copy the downloaded file to the keys subfolder of the Data Link Server installation folder.

Open the application.propertiesconfiguration file and ensure that the security.token.enabled is uncommented and set to true.

By default, the Data Link Server works over HTTP. It is strongly recommended that you configure an SSL certificate so that Telerik Platform can communicate with the Data Link Server over HTTPS.

Take these steps to enable SSL:

Acquire an SSL certificate.

The supported format is the Java KeyStore (JKS) format, the standard Java format. You can generate a JKS using the keytool command-line utility. The same tool is also used for importing existing certificates into the keystore. For complete instructions see the official Apache Tomcat documentation.

After you have acquired the keystore file containing the certificates, configure the ssl.* set of application.propertiesconfiguration options.

Use the information in this paragraph only when you have a running Data Link Server and want to update it with the latest version of the package. In the steps below you will learn how to install the new application package while preserving the already applied configuration.

Follow the steps for Uninstalling the Service (in case you are running the server as a system service) or stop the running instance of the Data Link Server from the console window.

Backup the following files from the current installation folder of the Data Link Server.